Automatic electric water heater



'M. c. CRAWLEY AUTOMATIC ELECTRIC WATER HEATER Filed Sept. 14, 1927 May 27, 1930.

ATTORNEYS Patented May 27, 1930 UNITED STATES PATENT OFFICE MANSFIELD C. CRAWLEY, 03' GROTON, NEW YORK, ASSIGNOB '10 CHARLES D. DAVIS,

OF WASHINGTON, DISTRICT FIELD, NEW JERSEY OF COLUMBIA, AND WILLIAM B. DAVIS, OF WEST- AUTOMATIQ ELECTRIC WATER HEATER Application filed September 14, 1927. Serial No. 219,494.

the predetermined temperature. Water heating apparatus of this type is adapted for many uses where a supply of hot water is desirable. The apparatus shown and described herein is especially designed for household use.

An object of the invention is to provide a water heating apparatus having improved means for automatically controlling the electric heating current.

Another object of the invention is to provide for the automatic control of the heating current by means operated by hydrostatic pressure in response to changes in the temperature of the water.

In the drawings:

Fig. 1 is a vertical sectional view of the heating apparatus with the current controlling parts in the positions for the water;

Fig. 2 fragmentary vertical section upon larger scale showing the current-controlling parts moved to interrupt current; and

Fig. 3 a horizontal section taken on the line 3-3 of Fig. 2.

Referring by numerals to the various parts of the apparatus, 1 designates an upright closed water tank of suitable capacity. A

.plate 2 forms the lower end wall of the tank and is removably secured to the body of the tank by screws or bolts 3. A water inlet pipe connection 4 is threaded through the center of the plate 2, and an outlet pipe connection 5 is threaded into the upper end of the tank. Centrally formed upon the upper face of the plate is a circular boss 6. This boss is formed with a. circular channel 7 which is concentric with the water inlet. The side walls of the channel 7 are undercut as'at8 and its bottom is formed with two spaced, concentric grooves 9. Disposed at the bottom of the channel 7 are two rings 10 and 11 of suitab e insulating material, the undersides of the ringsbem formed to fit in the grooves 2 and posltion t e rings in. spaced concentric relation. Two flat rings 12 and 13 of suitable conductin material are supported by the insulation rings 10' and 11 and to each of the former is connected a conducting rod 14. At its under face the plate 2 is formed with two bosses 15, and the insulation rings 10 and 11 are formed with tubular extensions 16 which extend downward through 0 enings in the bosses. The rods 14 pro ect t rough the extensions 16 and have nuts threaded upon their lower ends for clamping the current-conducting wires 17 and 18 thereto. Cap nuts 19 are threaded upon the bosses 15 and enclose said rods and conducting wires at their points of attachment.

Supported upon the conducting ring 12 is a tubular, cylindrical terminal or electrode 20, and supported upon the ring 13 is a smaller tubular, cylindrical terminal or electrode 21. These two terminals are formed of carbon. They are of the same height and are supported in spaced relation. A suitable fusible insulatin material 22 is poured into the channel Z to ll the latter and surround the lower ends of the terminals and the rings supporting them. This material flows into the undercut portions of the channel and through transverse openings 23 in the terminals. When hardens the terminals are held rigidly in place. The carbon terminals are preferably coated except on their opposed faces with a suitable water-proof insulating enamel 24. This insulating material may be applied to the carbon terminals in any suitable manner,

by baking or otherwise.

An upright open-ended tubular member 25 stufling box 30, and a plunger 31 is mounted to rec1 rocate throug it a These various efine a water-ti ht chamber. The

' ower end of the stufiingox is threaded into reciprocated by hydrostatic pressure in response'to changes in tem erature oi the water in the tank as will be ully explained later in the specification. .In its reciprocation the plun er carries with it a current interrupter whic is adapted to. be interposed between the terminals 20 and 21 and withdrawn therefrom to vary the current. This current interru ter is in the form of a cylindrical tubular shield 32 of insulating material. It is con nected to theplunger by means of a spider 33 formed with a central portion, encircling i loosel threa ed upon the lower end of t e plunger. The tubular member is formed with ver- 'tical slots 37 to provide clearance for the the lower end of the plunger, and four arms which extend radially outward from the plun r and then upwardly within the inner terminal 21, and outwardly and downwardly at their upper (ends. The shield is secured to the downturned portions of said ends b clips 34 held in clamping engagement wit the shield by screws 35. The spider 33 is supported at its center b a nut 36 arms of the spider, and a nut 38 is threaded upon the upper end of said member to ri 'dly hold itaround the stufling box. The s eld is adapted to be received in the annular space between the terminals 20 and 21 and in-its lowermost position its lower edge rests upon the insulation 22. Its length is such that in this position it still extends a material distance above the terminals. In its uppermost position it is not entirely. with'drawn, its lower end remaining between the terminals.

In the use of the apparatus the closure cap 28o'f the chamber 26 is removed, the plunger 31 is raised to its uppermost position so that a material portion 0 its length projects into the chamber, and the chamber'is completely filled with water at normal temperature. The cap 28 is then replaced and water is admitted to the tank through the inlet 4. Preferably the inlet remains constantly connected to the water main so that the tank will be always full of water at full'main pressure. The terminals and the chamber 26 are then entirely submerged, and' the plunger is exposed at its outer end to the water in the tank and at its inner end to the water in the chamber. The walls of the chamber are formed of a. material possessing good heat conductivity in order that a chan e in the temperature of the water in the will be accom anied bya substantially corresponding 0 ange in the water confined in the chamber.

with the plunger and the insulating shie or interrupter 32 fully elevated the plunger is positively eld up by the hydrostatic pressure exerted u on its lower end by the unheated water in t e tank, as a descent of the El r would cause a vacuumin the closed 0 am r 26. In this position of the plunger the spider 33 and the shield are held elevated by the nut 36 upon the plunger. The current is then free to flow across the s ace between the terminals, with the result In the initial adjustment of the apparatulai J at the water at the lower end of the tank will be heated F and will flow upwardly past theterminads and past the shield to the upper portion of the tank. Near their lower ends the term1- nals are formed with transverse openings 39 to freely admit the water'to the heatin space between the terminals.. When the heatin current has continued long enough to heat t e volumeof water surrounding the chamber 26, heat will beconducted through the walls of the, chamber to the small confined volume of water therein. Theheat' of the latter tends to expand it so that a ow of hydrostatic pressure is exerted upon the upper end of the plunger. When the temperature increases to a predetermined degree this pressure -will overcome the opposin hydrostatic pressure upon the lower end 0 the plunger and move the plunger downward. The descent of the plunger permits the spider 33 and the shield 32 to gravitate and mterpose the shield between the terminals to interrupt the flow of current. If the hi h temperature continues and increasesv s cientlly; the plunger will be forced down far enoug to permit the shield to gravitate until it abuts the insulation 22 at the bottom of the tank and entirely separates the terminals. If, however, some of ,the heated water is withdrawn, colder water will flow around the chamber 36 arresting the expansion of the water therein and the descent of the plunger and the shield.- v

Ifthe temperature of the Water in the tank should fall to a predetermined degree, due to the interruption of the current or a with: drawal of hotwater, with a consequent inflow of cold water through the inlet 4, heat Will be conducted from the confined volume minals to permit a resumption of the heating current therebetween. The up)ward movement of the plunger is limited y contact of the central portion of the spider with the gland 40 of the stufling box. 5

Thus the current is automatically controlled in accordance with the heating requirements of the water in the tank. The current interrupter is moved to operative or inoperative position by changing hydrostatic pressure due to'exchanges of heat between the water in the tank and the contively support said shield withdrawn from said electrodes independently of the water in said tank; and means actuated by changes in temperature of water in the tank to operate supporting means to interpose said shield betten said electrodes when the temperature oi he water in the tank rises, andto positively withdraw said shield when the temperature of the water is reduced.

2. In a water heater, the combination of a tank; a pair of electrodes spaced apart in said tanlrrin position to be submerged in the water; electrical conductors connected to said electrodes; an insulating shield adaptedto reciprocate and to be interposed between said electrodes and to be withdrawn therefrom; normally stationary means to positively support said shield withdrawn from said electrodes independently of the water in said tank; and means actuated by water pressure due to changes in temperature of water in the tank to operate said supporting means to interpose said shield between said electrodes when the temperature of the water in the tank rises, andv to positively withdraw said shield when the temperature of the water is reduced.

3. In a water heater, the combination of a tank; a pairof electrodes spaced apart in said tank in position to be submerged in the water; electrical conductors connected to said electrodes; an insulating shield adapted to reciprocate and to be interposed between said electrodes and to be withdrawn therefrom; normally stationary means to ositively support said shield withdrawn rom said electrodes independently of the water in said tank; and means actuated by tluid due to changes in temperature oi water in the tank to operate said supporting means, to interpose said shield between said electrodes when the temperature of the water in the tank rises, and to positively withdraw said shield when the temperature of the water is reduced.

' ,4. In a water heater, the combination of a tank; a pair of annular electrodes arranged one'within the other and spaced apart in the tank in position to be submerged in the water in said tank; electrical conductors connected to said electrodes; an annular insulating shield adapted to reciprocate and to be interposed between said electrodes and to be withdrawn therefrom; normally stationary 4 means to positively support said shield withdrawn from-said electrodes independently of the water in said tank; and means actuated by changes in temperature of water in the tank to operate said supporting means to interpose said shield between said electrodes when the temperature of the water in the tank rises, and to positively withdraw said shield when the temperature of the water is reduced.

5. In a water heater the combination of a tank; a pair of annular electrodes arranged one within the other and spaced apart in the tank in position to be submerged in the water in said tank; electrical conductors connected to said electrodes; an annular insulating shield adapted to reciprocate and to be interposed between saidelectrodes and to be withdrawn therefrom; normally stationary means to positively support said shield withdrawn from said electrodes independently of the water 1n said tank; and means actuated by water pressure due to changes in temperature of water in the tank to operate said supporting means to interpose said shield between said electrodes when the temperature of the water in the tank rises, and to positively withdraw said shield when the temperature of the water is reduced.

6. a water heat-er, the combination of a tank; a pair of annular electrodes arranged one within the other and spaced apart in the tank in position to be submerged in the water in said tank; electrical conductors connected to said. electrodes; an annular insulating shield adapted to reciprocate and to be interposed between said electrodes and to be withdrawn therefrom; normally stationary means to positively support said shield withdrawn from said electrodes independently of the water in said tank; and means actuated by fluid pressure due to changes in temperature of water in the tank to operate said supporting means to interpose said shield between said electrodes when the temperature of the water in the tank rises, and to positively withdraw said shield when the temperature of the water is reduced.

7 In a water heater, the combination of a tank; a pair. of electrodes spaced apart in said eIectrical conductors connected to said electrodes; an insulating shield adapted to reciprocate and to be interposed betweensaid electrodes and to be withdrawn therefrom; normally stationar means to positively support said shield wit drawn from said electrodes independently of the water in said tank; and

mechanism actuated by changes in temperature of water in the tank to operate said sup porting means to interpose said shield between said electrodes when the temperature of the water in the tank rises, and to posi-- tively withdraw said shield when the temperature of the water is reduced.

.8. In a water heater, the combination of a tank; a pair of electrodesspaced apart in said tank in position to be submerged in the water; electrical conductors connected to said electrodes; an insulating shield adapted to reciprocate and to be interposed between said electrodes and to be withdrawn therefrom; normally stationary means to positively support said shield withdrawn from said electrodes independently of the water in said tank; and mechanism actuated by water pressure due to changes in temperature of water in the tank to operate said supporting means to interpose said shield between said electrodes when the temperature of the water in the tank rises, and to positively withdraw said shield when the temperature of the water is reduced.

9. Ina water heater, the combination of a tank;"a pair of electrodes spaced apart'in said tank in position to be submerged in the water; electrical conductors connected to said electrodes; an insulating shield adapted to reciprocate and to be interposed between said electrodes and to be withdrawn therefrom; normally stationary means to positively support said shield withdrawn from said-electrodes independently of the water in said tank; and mechanism actuated by fluid pressure due to changes in temperature of water in the tank to operate said supporting means,

to interpose said shield 'between said electrodes when the temperature of the water in the tank rises, and to positively withdraw said shield when the temperature of the wa ter is reduced.

' 10. In a water heater, the combination of a tank; a pair of annular electrodes arranged one within the other and spaced apart in the tank in position to be submerged in the water .in said tank; electrical conductors connected to said electrodes; an annular insulating shield adapted to reciprocate and to be interposed between said electrodes and to be withdrawn therefrom; normally stationary means to positively support said shield withdrawn from said electrodes independently of the water in said tank; and mechanism actuated b changes in temperature of .water in the tank to operate said supporting means to interpose said shield between said electrodes when the temperature of the water in the tank rises, and to positively withdraw said shield when the temperature of the water is reduced.

11. In a water heater, the combination of a tank; a pair of annular electrodes arranged one within the other and spaced apart in the tank in position to be submerged in the water in said tank; electrical conductors connected to said electrodes; an annular insulating shield adapted to reciprocate and to be interposed between said electrodes and to be withdrawn therefrom; normally stationary means to positively support said shield withdrawn from said electrodes independently of the water in said tank; and mechanism actuated by water pressure due to changes in temperature of water in the tank to operate said sup porting means to inter ose said shield bet'ween sald'electrodes-when the temperature of the water in the tank rises, and to positively withdraw said shield when the temperature of the water is reduced. I

12. In a water heater, the combination of a tank; apair of annular electrodes arranged one within the other and spaced apart in the tank in position to be submerged in the water in said tank; electrical conductors connected to said electrodes; an annular insulating shield adapted to reciprocate and to be interposed between said electrodes and to be withdrawn therefrom normally stationary means to positively support said shield withdrawn from said electrodes independently of the water in saidtank; and mechanism actuated by fluid pressure due to changes in temperature of water in the tank to operate said supporting means to interpose said shield between said electrodes when the temperature of the water in the tank rises, and to positively withdraw said shield when the temperature of the water is reduced.

'13. In a water heater, the combination of a tank; a pair of carbon electrodes spaced apart in said tank in position to be submerged in the water; electrical conductors connected to said electrodes ;,an insulating shield adapted toreciprocate and to be interposed between said electrodes and to be withdrawn therefrom; normally stationary means to positively support said shield withdrawn from said electrodes independently of the water in said tank'; and means actuated by changes in tem- .perature of water in the tank to operate said supporting means to interpose said shield be-' tween saidelectrodes when the temperature of the water in the tank rises, and to positively withdraw said shield when the temperature of the water is reduced.

14. In a water heater, the combination of a tank; a pair of carbon electrodes s aced apart in said tank in position to be submerged in the water; electrical conductors connected to said electrodes; an insulating shield adapted to reciprocate and to be inte osed between said electrodes andto be -w't drawn therefrom; normall stationary means to positively support'sai shield withdrawn from said electrodes independently of the water in said tank; and means actuated by water pressure due to changes in temperature of water in the tank to 0 erate said supporting means to interpose said shield between said electrodes when the tem erature of the water in the tank rises, an to positively withdraw said shield when the temperature of the water is reduced. v

15. In a water heater, the combination of a tank; a pair of annular carbon electrodes arranged one within the other and spaced means to interpose said shield between said v electrodes when the temperature of the water in the tank rises, and to positively withdraw said shield when the temperature of the water is reduced.

16. In a water heater, the combination of a tank; a pair of annular carbon electrodes arranged one within the other and spaced apart in the tank in position to be submerged in the water in said tank; electrical conductors connected to said electrodes; an annular insulating shield adapted to reciprocate and to be interposed between said electrodes and to be withdrawn therefrom; normally stationary means to positively support said shield withdrawn from said electrodes independently oi? the water in said tank; and means actuated by water pressure due to changes in temperature of water in the tank to operate said supporting means to interpose said shield between said electrodes when the temperature of the water in the tank rises, and to positively withdraw said shield when the temperature of the water is reduced.

17. In a water heater, the combination of a tank; a closed water chamber in said tank in position to be submerged in the water therein; a pair of terminals spaced apart in the tank in position to be submerged in the water in said tank; an insulating shield adapted to reciprocate and to be interposed,

in between said terminals and to be withdrawn therefrom; means extending into the closed chamber and adapted to be reciprocated therein and to be actuated by pressure due to changes in temperature of the water in said closed chamber; and means connecting said reciprocable means to the said insulating shield whereby said shield will be interposed between the electrodes when the water in the closed chamber is raised in temperature, and will be withdrawn from between said electrodes when the said temperature is lowered.

18. In a water heater, the combination of a tank; a closed water chamber in said tank in position to be submerged in the water therein; a pair of terminals spaced apart in the tank in position to be submerged in the water in said tank; an insulating shield adapted to reciprocate and to be interposed in between said terminals and to be withdrawn therefrom; a plunger extending into the closed chamber and adapted to be reciprocated therein and to be actuated by pressure due to changes in temperature of the water in said closed chamber; and means connecting said reciprocable plunger to the said insulating shield whereby said shield will be interposed between the electrodes when the water in the closed chamber is raised in temperature, and will be withdrawn from between said electrodes when the said temperatureis lowered.

19. A liquid-heating device comprising means forming a liquid-tight chamber, with a heat-conducting wall; means to support said chamber within a liquid tank with its heat-conducting wall exposed to liquid in the tank at its outer face and to liquid in said chamber at its inner face; a plunger mounted to reciprocate through one wall of said chamber and'having-its inner end exposed to the liquid in the chamber and its outer end exposed to the liquid in the tank; electrical means to heat the water in the tank; and means operated by the reciprocation of said plunger to vary the heating eflect of said electrical means.

20. A liquid-heating device comprising means forming a liquid-tight chamber, with a heat-conducting wall; means to support said chamber within a liquid tank with its heat-conducting wall exposed at its outer face to liquid in the tank and at its inner face to liquid in the chamber; a shiftable member to vary the size of said chamber, subject at opposite faces to opposing pressures of the liquid in the tank and the liquid in the chamber; electrical means to heat the liquid in the tank; and means operated by the movements of said shiftable member to vary the heating eiiect of said electrical means.

21. A liquid-heating apparatus comprising. a tank; a pair of tubular, concentric, spaced electric terminals mounted in said tank in upstanding positions; means forming a liquidtight chamber, with heat-conducting walls; means supporting said chamber within the tank in a position over the center of the terminals; a plunger mounted to reciprocate vertically through the lower Wall of the chamber and have its inner end exposed to liquid in the chamber and its outer end exposed to liquid in the tank; an annular insulating barrier carried by said plunger to reciprocate with it and adapted to be interposed between the terminals and interrupt the current when the plunger is moved down. 22. A liquid-heating apparatus comprising a tank; a pair of tubular, concentric, space electric terminals mounted in said tank at the lower end thereof in upstanding positions; means forming a li uid-tight chamber with 10 heat-conducting wa ls; means supportln said chamber in the tank; a plunger mounte to reciprocate vertically through one wall of said chamber and have its inner end exposed to liquid in the chamber and its outer end exposed to liquid in the tank; an insulating barrier carried by said plunger to reciprocate with it and adapted to be interposed between. the terminals and interrupt the current when the plunger is moved down; a liqzo uid inlet at the lower end of the tank, opening into the space defined by the inner terminal; andka liquid outlet at the upper end of the a tan 23. In a water heater, the combination of a tank; a pair of electrodes spaced apart in said tank in position to be submerged in the v water; electrical conductors connected to said electrodes; an insulating shield adapted to reciprocate and to be interposed between said 80 electrodes and to be withdrawn therefrom;

normally stationary means to positively support said shield withdrawn from said electrodes; and means actuated by water pressure due to changes in temperature of water in the tank to operate said supporting means to gradually and progressively interposesaid shield between the said electrodes as the temperature of the'water in the tank rises, and to ositively, gradually and progressively 4o wit draw said shield as the temperature of the water is reduced.

24. In a water heater, the combination of a tank; a pair of annular electrodes arranged one within the other and spaced apart in the tank in position to be submerged in the water in said tank; electrical conductors connected to said electrodes; an annular insulating shield adapted to reciprocate and to be inter: posed between said electrodes and to be withdrawn therefrom; means to ositively support said shield withdrawn rom said electrodes; and means actuated by fluid pressure due to changes in temperature of water in v the tank to gradually and progressively interpose, said shield between said electrodes when the temperature of the water in the tank rises, and to'positively, gradually and progressively withdraw said shield when the I temperature of the water is reduced. In testimony whereof I hereunto aifix my signature.

MANSFIELD C. CRAWLEY. 

